This invention relates to articulated crane-type machines, such as hydraulic excavators, and is more particularly directed to machines of the type having a boom, a stick, and a tool attachment articulated with respect to one another, in which one or more sticks are interchangeably connectable to the boom.
A typical excavator or similar heavy equipment apparatus has an attachment arm formed of an articulate boom and a stick rockably mounted on the boom, with a bucket, blade, shear, grapple, fork, or other tool attached to the end of the stick. Hydraulic cylinders are mounted on the attachment arm to raise or lower the stick in the same plane. A tool cylinder connected between the tool and the stick operates the tool, i.e., raises or lowers the bucket, opens or closes the shear, etc.
Different tools are often required for an operation. If these are to be joined to the same excavator or other similar apparatus, it is required to remove the tool from the stick, or to remove the stick from the boom to substitute a different tool or stick. The stick is taken off the boom to substitute a different stick, for example, a stick of a different length or width, or a stick having a different tool formed unitarily on it. A pivot pin is driven from the articulated joint between the distal end of the boom and the stick, and an eye pin is driven from the connection of the stick with the stick cylinder rod. Then the substitute stick has to be manipulated, the pivot pin driven back into place, and the eye pin driven into place. After that, hydraulic lines have to be run from the excavator body to the tool cylinder. Aligning the stick with the boom is difficult. This operation can require the work of a crew of several skilled workmen and can consume an hour or more.
Quick-disconnect mechanisms have been well known for the tool end of the stick, for example, to facilitate the interchange of buckets of different sizes or configurations. This has been especially proposed with respect to backhoe attachments in the field. However, no such satisfactory quick-disconnect mechanism has been known for use between the stick and the boom.
It is often required to use attachments with integral stick and tool configurations, for example, a large shears employed for the recycling of steel scrap. It is well accepted now that one-piece shear-stick arrangements are far superior to a combination of a stick and an interchangeable or pin-on shear. This is so, at least in part, because of the structural soundness of the shear-stick and the relatively low installation and removal time requirements of an integral shear-stick. In a steel scrapping operation, it is often necessary to change from a shear to a grapple, clamshell, or other attachment quickly and without a crew in attendance. However, this cannot be done unless there are some means provided for the quick connecting and disconnecting of the stick to the boom of the excavator machine employed for that purpose.
If quick disconnect mechanism presently used on wheel loaders between the loader arms and buckets were used between the boom and the stick, the stick may tend to wobble somewhat because of play in the mechanism amplified over the length of the stick.